Time

deep that contained fifteen thousand tons of waste mixed with uranium and plutonium. It was very unstable; it had already suffered two hydrogen explosions, spraying radioactive waste everywhere.

“Jesus,” she said. “What a folly. Another generation’s dreams of cheap power. And we have to live with the shit forevermore.”

“Well, it didn’t go entirely to plan,” he conceded. “Originally this was going to be a nuclear park. Six reactors. But the technology was ahead of its time.”

“Ahead of its time? “

“Everything was within the guidelines of the time. Even the secrecy, if you want to know. You have to remember it was the Cold War. They didn’t have the same obsession with safety we have now. An obsession that has stunted us since, conservatively, 1970. And guess what? The local people now love the plant. If it never produces another watt, Dounreay is going to be around for a hundred years. Four generations of high-quality, highly skilled local employment. Because it will take that long to decommission it.”

“So tell me something else. If the U.K. government shut this place down in the 1990s, how come you managed to acquire enriched uranium here?”

He said gently, “There’s nothing illegal.”

“My God, Malenfant.”

“Look.” He dug a small, crumpled softscreen out of his pocket, unfolded it with stiff fingers. It showed an image of something like a rocket engine, a sky-blue nozzle mounted by complex machinery, tall and skinny. The diagram was labeled with spidery text much too small to read. Malenfant said, “This is what we’re building. It’s a nuclear reactor designed for space missions. Here’s the reactor at the top.” He pointed with a thumbnail and worked his way down. “Then you have pumps, shielding, and a radiator. The whole thing stands about twelve feet tall, weighs about a ton. The reactor has a thermal output of a hundred and thirty-five kilowatts, an electrical supply of forty kilowatts…

“Emma, you have to understand. If we have humans aboard a new Nautilus, we have a mission an order of magnitude more power-hungry than Sheena’s. And then there are the power requirements for surface operations. To generate the juice we need from a solar array you’d need an area half the size of a football field, and weighing maybe ten times as much. Even the BDB couldn’t lift it.”

“And this is what you’re planning to build?… Oh. You’re already building these things. Right?”

He looked pleased with himself. Look what I did. “We hired Russian engineers. Dug some of them out of retirement, in fact. The U.S. never developed nuclear power sources beyond radioisotope heat generators we flew on unmanned missions. In fact the Clinton administration shut down our space nuclear power research program. What can you do but condemn that? When we gave up nuclear power, we gave up the future.

“But the Russians flew nuclear power sources on reconnais-

sance missions back in the 1960s, and they even test-flew a de-

sign called Topaz, which is what we based this baby on. Of

course we were able to tune the design a hell of a lot.”

“Malenfant—”

He tapped the little screen. “All we need is fifty pounds of en-

riched U-235, in the form of uranium dioxide pellets. The mod-

erator is zirconium hydride, and you control the reaction by

rotating these cylinders on the outside of the core, which—”

“How are you smuggling this shit into the Mojave?”

“Smuggling is a harsh word.”

“Come on, Malenfant. Those desert skies are pretty clear. Surveillance satellites—”

“You really want to know? All the satellites’ orbital elements are on the Net. You can work out where they will be at any minute. You just shut down until they’ve passed overhead. Even better, make sure you hit the night shift at the National Imagery and Mapping Agency down at Fairfax. There’s always something more interesting to look at than pictures of an old buzzard like me jerking off in the desert.”

“Act now; justify later. Like the BDB launch. Like most of the actions in your life.”

“Emma, you have to trust me on this one. If I can run a Topaz or two, prove it’s safe, I can get the authorizations I need. But I have to get the nuke stuff to run the tests in the first place.”

“And the citizens of Las Vegas have to trust you, too, until enriched uranium comes raining down out of the sky? You know, you’re a dreamer, Malenfant. You actually believe that one day we will all come to our senses and agree with you and hail you as a hero.”

“I’m already a hero.” He winked. “There are T-shirts that say it. Look, Emma. I won’t pretend I’m happy with everything I’m having to do. No more than you are. But we have to go on. It’s not just Bootstrap, the profits: not even about the big picture, our future in space—”

“Cornelius. The Carter catastrophe. Messages from the future.”

He eyed her. “I know how you’re dealing with this. You’ve put it all in a box in your mind that you only open when you have to. But it s real, Emma. We both saw those neutron pulses.”

“Neutrinos, Malenfant,” she said gently.

“We’re in this too deep, Emma. We have to go on.”

She closed her eyes. “Malenfant, patience has always been your strength. You don’t need lousy Russian reactors and dubious uranium shipments. Take your time and find another way to build your spaceship.”

His voice was strained. “I can’t.”

And, of course, she knew that.

He bent down and kissed the top of her head.

She sighed. “You know I won’t betray you. I’ve been sucked in too deep with you for a long time, for half my life. But do you ever consider the ethics of implicating me, and others, in this kind of shit? You have to be open with me, Malenfant.”

“I will,” he said. “I promise.”

She knew, of course, that he was lying.

In fact she was more useful to him if she didn ‘t know. It made her denials that much more effective. It probably even protected her a little, too.

But that wouldn’t be uppermost in his mind; it was just an incidental. What drove Malenfant was maximizing her utility in the drive toward his ultimate goals — -just like any of the tools he deployed.

She understood all that. What she really didn’t know, in her heart of hearts, was why she continued to put up with it.

She linked her arm through his, and they huddled together against the wind, looking over Dounreay. Mist swept in off the sea, covering the plant in grayness.

Reid Malenfant:

How can we turn asteroid rock into rocket fuel? Sounds like

magic, doesn’t it?

First we’ll crack asteroid water into hydrogen and oxygen with electrolysis. Remember high school science classes, the Pyrex beakers and the wires and the batteries? All you have to do

is pass an electric current through water to break it down. That’s

what we do. But the units we use are a little more advanced.

Slide, please.

This is a solid polymer electrolyte, or SPE, electrolyzer. What you have is sandwiched layers of electrolyte-impregnated plastic separated by metal meshes. The whole assembly is compressed by metal rods running the length of the stack.

SPEs have been used extensively on nuclear submarines and on the space station. They run for thousands of hours without maintenance.

As for the methane, we will extract some directly from the asteroid material, and more by processing carbon dioxide. We use something called a Sabatier reactor. Slide. We liquefy the hydrogen from the electrolyzer banks, and feed it into the reactor with carbon dioxide. Out the other side comes water and methane — which is just a compound of carbon and hydrogen. The reaction is very efficient, ninety-nine percent in fact, and is exothermic, which means it requires no input of heat to make it work, just the presence of a ruthenium catalyst.

Sabatier units have been used in space before, for life-support applications. They have been tested by NASA and the Air and Space Force and have also been used on the space station.

There is further information in your packs on how we intend to optimize the ratios of the methane-oxygen bi-propellant, and various subsidiary processes we need. We can show you a demonstration breadboard prototype. Oxygen-hydrogen is of course the most powerful chemical-rocket propeOant of all. But hydrogen is difficult to liquefy and store: low temperature, large bulk. Methane is like oxygen, a soft cryogenic, and that guided our choice.

AH this sounds exotic. But what we have here is very robust engineering, gaslight-era stuff, technologies centuries old, in fact. It’s just a novel application.

Ladies and gentlemen, mining an asteroid is easy.

Slide, please.

Sheena 5:

The babies were already being hatched: popping out of their dissolving eggs one by one, wriggling away, alert, active, questioning. With gentle jets of water, she coaxed them toward the sea grass where they would browse until they were mature.

She tried not to think about what would happen then.

Meanwhile, she had work to do.

When Sheena powered up the rock eater, she was more nervous than at any time since the landing itself. She lay as still as she could inside her waldo glove and tried to sense the eater’s systems — the gripping tracks that dug into the asteroid’s loose surface, the big gaping scoop of a mouth at the front, the furnace in its belly like a warm heart — as if she herself had become the fat clanking machine that would soon scuttle crablike across the asteroid floor.

She understood why she felt so tense.

The rock eater was a complex machine. It would need monitoring as it chewed its way around the asteroid, to make sure it didn’t burrow too deeply into the surface, or spin its tracks on some loose patch of rock and throw itself into the emptiness of space, beyond retrieval.

But it was no more difficult to control, in principle, than the little firefly robots, and she was used to them by now; in fact she had come to enjoy deploying six, seven, eight of them at once, a shoal of robots, relishing the chance to show offher skill to Dan.

It wasn’t even the importance of this operation for her mission that made her anxious. She knew the fireflies had done no more than measure, weigh, analyze, monitor. Now, for the first time, she was going to do something that would change the asteroid, to make something out of its loose, ancient substance. To fail would mean that she could not succeed with